/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
static void CombineWithAdditiveAnimations ( int32 NumAdditivePoses, const FTransformArrayA2 ** SourceAdditivePoses, const float * SourceAdditiveWeights, const [FBoneContainer](API\Runtime\Engine\FBoneContainer) & RequiredBones, FTransformArrayA2 & Atoms )